RICHMOND — Gasoline prices throughout California could reach $4 a gallon at the pump by next week and $4.50 by Labor Day as a result of the fire that hobbled Chevron’s East Bay refinery, oil analysts said Tuesday.

Spot prices — the price set before gasoline is delivered to the pump — jumped 36 cents in the Bay Area and 31 cents in the Los Angeles area Tuesday, according to markets tracked by Bloomberg News. Analysts said the 36-cent spike was the largest one-day increase on record.

“With the spike in spot gasoline prices today, you are looking at average pump prices in the Bay Area ranging from $4 to $4.10 a gallon within a week or so,” said Tom Kloza, chief oil analyst at the Oil Price Information Service. Currently, Bay Area prices are in the $3.70 range.

The outage at the Richmond refinery, which produces 20 to 25 percent of Northern California’s gasoline and half of the jet fuel used at Bay Area airports, comes at a time when inventories are relatively low on the West Coast as refiners prepare to switch over from their summer blends to winter blends, as required by state regulators.

“This is a perfect storm,” said Bob van der Valk, a Montana-based fuel price analyst. “You have refineries at their lowest inventory levels.”

Monday’s fire shut down one of the units that distills crude oil, and Chevron had no word on when the unit might resume operations. “We are undertaking a full assessment of the refinery to see what can be started and when,” said Chevron spokesman Lloyd Avram.

The refinery will not be back online anytime soon, Paul Sankey, an analyst with Deutsche Bank, warned in a research note Tuesday.

“With the stringency of California regulations, the location of Richmond in a residential area and very visible to the San Francisco population, we expect this outage to last longer rather than shorter,” Sankey said, adding that it may take “several months at least” to return to full production.

That grim assessment was shared by van der Valk, who said: “The Richmond refinery will have to be largely rebuilt.”

The gas price surge resulting from the fire is partly due to the nature of the state’s gasoline market. Strict environmental rules require a specific blend of gasoline to be sold in California. As a result, relatively few substitutes exist in other regions that could replace any reduction in gasoline inventories in California.

“It is a lot harder to substitute gasoline in California from other markets,” said Scott Anderson chief economist with San Francisco-based Bank of the West. “That is why you get this sort of a quick response to changes of supply here. The supply of gasoline is inelastic.”

Any sustained increase in gasoline prices could damage the statewide economy, which has struggled to recover from the recession.

“Just at a time when California residents were counting on lower prices to add more disposable income, this refinery fire could put a dent in that,” Bank of the West’s Anderson said. “These sorts of shocks that raise prices quickly hurt economic growth and consumer spending.”

Chevron’s Richmond refinery is the largest in the Bay Area, with a production capacity of about 244,000 barrels a day. Chevron did not provide immediate information about the impact of the fire on production, but said the fire will not result in gas lines in California.

Still, the spike in fuel costs suggests that traders are betting on much higher gasoline prices, analysts said.

“The market is rendering a judgment,” Kloza said. “The market says it is worried. That’s why gasoline prices are going up. California is not going to run out of gasoline. But we are going to have a spike.”

The current spike in prices could extend for a number of weeks — and it could be widespread.

“We are going to get $4 a gallon on the West Coast this week,” van der Valk said. “We are going to get $4.50 by Labor Day. This is going to be bad for California, Oregon, Washington and Nevada.”

More in News

SAN JOSE -- Grenades were discovered at an estate sale Monday, prompting the evacuation of about 10 homes near the San Jose Country Club, according to the Santa Clara County Sheriff's Office. Deputies were called to the 300 block of Gordon Avenue, near Greenside Drive, about 4:10 p.m., said Sgt. Rich Glennon. Get breaking news with our free mobile app....